diff --git a/session/environment_test.go b/session/environment_test.go
index b3b3bb85..5edcc0ee 100644
--- a/session/environment_test.go
+++ b/session/environment_test.go
@@ -263,6 +263,10 @@ func TestSessionEnvironmentGetInt(t *testing.T) {
 	} else if i != 1234 {
 		t.Fatalf("unexpected integer: %d", i)
 	}
+
+	if err, _ := env.GetInt("unknownint"); err == nil {
+		t.Fatalf("expected error (unknown key): %v", err)
+	}
 }
 
 func TestSessionEnvironmentSorted(t *testing.T) {